Periodic signal e.g. of capacitive voltage transformers disturbance component suppressing method for HT capacitive voltage divider

摘要

HV and low-voltage capacitors (Ca,Cb) are connected in series by a coaxial cable (11), and the low-voltage capacitor (Cb) shunted by a resistance (R2) is placed in parallel with an operational amplifier (11) referred to earth. The output (u(t)) is applied to a microprocessor (14) which detects and samples its values at intervals of e.g. 3 and 18 ms after a zero-crossing. The perturbing component of the voltage is computed and subtracted to obtain the useful signal, which is fed back (19) from a power transformer (17) at the output of a power amplifier (16).